East Credit River Tributary Weir.
Phases 1 and 2 of the East Credit River Tributary Weir Removal Project were recently completed by Credit Valley Conservation. The Ontario Rivers Alliance is pleased to report that we contributed $15,000 towards the Project.
Removal of this weir reconnects 6 kilometres of coldwater Brook Trout habitat and access to that habitat within the upstream reaches of the tributary.
CVC approached the weir removal with a slow and gradual drawdown of the ponds between 2023 and 2024, which was very effective in meeting the Project’s goals and objectives. During construction, the release of sediment was well controlled and comparable to what a rain event would have produced. These types of pond mitigation projects often use this method to effectively manage sediment release and achieve cost-effectiveness.
Phase 1 of the Project was completed in July with the slow drawdown of the upper pond to allow the tributary to channelize and the flats to vegetate. Phase 2 was completed in mid-September with the removal of the weir materials, installation of a conifer deflector, seeding, planting of small shrubs on the sediment flats and restoration of other affected areas. The Naturalization Team will also conduct tree and shrub planting this fall. The Project is now in the post-construction monitoring phase.
The East Credit River tributary was dammed with a two-tiered weir to create a 0.2-hectare pond sometime between 1954 and 1989. The weir presented a physical barrier to fish passage during the low-flow conditions of Summer. The pond created a thermal barrier to fish passage by raising the temperature in this headwater tributary in an area known to have temperature-sensitive aquatic species, such as Brook Trout. The pond also degraded coldwater habitat by increasing stream temperature by approximately 4°C downstream and altered the natural geomorphology of the tributary. The weir also caused the tributary to backwater onto the adjacent property, increasing sediment deposition in the pond and increasing the risk of downstream sediment release, erosion, and flooding. The Project was located on private property in Caledon, Ontario.